Hi Jacky Smith -
Let's hope your friends rat(s) problem has "gone away".
It's possible that the rat(s) got a lethal dose of the rat poison and have gone off and died.
As long as your friend doesn't see any further evidence (rat droppings) of the presence of rats and the pest control person has re-inspected, I would be comfortable the the infestation has gone away.
Be sure to suggest to your friend gets rid of all the poison traps that the child could get into.
As a test to see if all the rats are gone, your friend may wish to put out a baited , old fashioned "rat trap" out to draw out any rats that have stayed behind.